In wireless communication systems, such as microwave systems, a transmission signal is generated by up-converting a base-band signal into a microwave signal, in which such up conversion is done using a single or multiple up-conversion frequencies in the microwave range. Using up-conversion frequencies in the microwave range may interfere with the operation of other nearby or co-located microwave channels, and may further or otherwise restrict the span of frequencies over which transmission of microwave signals can be made.